Silencer



J. A. DAY

April 21, 1936.

SILENCER Filed Nov.- 11, 1932 INVENTOR IV/x; /9, 5 1/ ATTORNEY r ll, A H n t atentea as AL rose John It. Day, lli'adison, Wis,

.latories;

Burgess Lab assignor to EL End, Madison, a

corporation of Delaware Application November ll, i932, Serial No. 6453.152

2 Claims. (@l. l3t==-l6l This invention relates to a silencer for internal combustion engines and more particularly to irn= provernents in silencers of the type disclosed in United States patent to F. H. Schnell, No.

' 1,811,762, granted June 23, 1931;

The silencer forming the subject matter or" the present application is particularly adapted for the silencing of carburetor intakes. It comprises a silencer which is highly emcient for purpose, and which occupies a minimum of. space. It is also adapted to have an air filter incor porated with it without adding appreciably to its size. The silencer of my invention offers a minimum of resistance to the flow of air therethrough.

It is also designed to provide a silencer which is particularly adapted for use with down-draft carburetors and which, even in the absence of a filter, minimizes the entrance of pa ticles of dirt and. dust into the carburetor with the air stream.

In the accompanying drawing, oi the invention are illustrated. inc,

Fig. l is a longitudinal, sectional view of one form or" my improved silencer;

Fig. 2 is a partial transverse view of the silencer shown in Fig. l; v

Fig. 3 is a longitudinal, sectional view of the silencer with an air filter attached;

Fig. 4 is a transverse or front view of the com blnation shown in Fig. 3;

Fig. 5 is a longitudinal, sectional view of a modl= fication oi the invention with the filtering unit incorporated therein in such a way as not to increase its size; and

Mg. 6 is a front view or the silencer shown in Fi 5.

In Fig. l, the outer shell of the silencer coin prises a concave substantially bowl=shaped mem ber ill, preferably formed of sheet metal. A similarly shaped foraminous member it is disposed interiorly oi the shell ill in spaced r lation thereto. The inner member M is supported by engagement of the two members at their pe ripheries. inner shell M is preferably drawn from a single piece of perforated sheet metal. in the space between the two members a filling H2 is arranged. The filling l2 comprises porous-packed material capable of absorbing sounds and gas-pressure-pulses, and may be termed briefly a gaseous pressure-wave absorbing ma= terial. losic fibers, mineral wool, steel, copper or other metallic wool or mimures thereof, exfoliated ver= several In the It may be wool, cotton or other cellu-=- miculite or other materials mentioned in the said =Schnell patent.

A. substantially flat annular plate l3 is arranged over the silencer and is attached at its outer periphery to the periphery oi outer shell it. Plate l3 and inner shell ll may be attached to outer shell ill by forming a radially outwardly extending head l9 in outer shell ill and. crimping the marginal portion of the latter over the edges of plate l3 and inner shell it. The attachment may be reinforced by spot welding at desired points. Plate l3 has a plurality of openings lt- (see Fig. 2) arranged radially about its axis and spaced inwardly from its outer periphery. 'lhese openings may be elongated clrcumferentially as shown. A rather short section idol a cylinder is attached intermediate between its ends to the inner periphery of plate 03. (Cylinder section it may be secu ed to the plate l3 by any suitable means such as spot welding. The portion of cyl= inder l5 located interiorly of plate 03 preferably iorarninous.

no annular convex or ring-shaped sheet metal member [16 is secured, as by means of spot weld-= ing, to the inner side or plate (13 and spaced from the inner shell M to form an air passage. 1-innular member 06 is iorarninous and is substan= tionally U=shaped in transverse section. its nner end is secured to the central cylinder member (15. Like inner shell I] l, annular member [16 is preferably drawn from a single piece of perforated, smooth-surfaced sheet metal. Plate l3, cylinder [15 and member l6 unite to form a closed annular shell, substantially i i-shaped in transverse see tion. A fling [ll of a gaseous pressure-=wave ab= sorbing aterial may be disposed within this shell. The iorannnous walls or the annular li-= shaped member and inner shell it may have interior 1' ings 2d of cheese cloth. Upenings M are arranged to register with the passage be= tween the inner shell l1] andannular member (16. The exterior portion of cylinder 05 is adapted to fit over the carburetor intake and may be held in place by means of clamp ill.

in ope.w ion openings [It form the entrance openings for incoming air and the space between annular member l6 and inner shell [ll forms the air pas. e from the entrance to the interior end of nder l5. An annular passage is thus provided for the air which converges smoothly and without angularity and unites in continuous fashion with e. centrally disposed, oppositely .rected circular passage through cylinder ii").

The circular passage connects directly with the carbtnetor. A passageway is thus provided through the silencer which is lined substantially throughout its length with a gaseous pressurewave absorbing material. Any sounds emerging from the carburetor, caused by the rush of air or the operation of valves, are silenced and any gas pulses caused by sudden changes of fiow conditions are absorbed.

For instance, it is known that when an intake valve is suddenly closed in the face of a rapidly moving stream of air momentary compression of the air stream occurs at the valve and this compression travels backwardly through the conduit or system in the form of a gas pressure pulse which creates a noise upon its emergence from the system. Any such pulses which travel backwardly through the carburetor are absorbed in the porous linings of the silencer duct.

One of the important advantages of my improved intake silencer lies in the fact that it ofiers practically no resistance to the fiow of air therethrough. Any resistance to air fiow, of course, reduces the efiiciency of the engine. The passage-way through the silencer is of a minimum length and the walls are of continuous smooth-surfaced perforated metal. Such surfaces ofiier practically no more resistance to the flow of a gas stream than do smooth, non-periorated metal surfaces. In the drawing opera= tion upon the perforated sheet metal, at those points where increased curvature occurs, the perforations may become distorted into the form of more or less narrow slits but this does not impair the emciency of their cooperation with the aseous pressure-wave absorbing material for suppressing noises. The walls are arranged to avoid excessive non-uniformity of cross sectional duct area with length and to avoid abrupt or angular direction changes which factors cooperate to prevent the building up of eddy currents which would otherwise interfere with and obstruct the free flow of the air stream.

Another advantage of my silencer lies in the fact that when it fits over the vertical intake of a down-draft carburetor, concave member it forms a covering and protection against dust and dirt particles that might otherwise drop into the carburetor intake. Furthermore, the entering air passes into the silencer in an upward direcl of the silencer.

tion so that the heavier dirt particles may be dropped from it before it enters.

If it is desired to incorporate an air filter with the silencer a device similar to that illustrated in Figs. 3 and 4 may be attached over the entrance The device comprises an annular sheet metal shell 2! which may have its side walls 22 project rearwardly beyond its rear wall 23. Spring clips 24 are attached at suitable circumferential intervals around the outer side wall 22 and these clips are adapted to snap over bead it to hold the filter in place. An annular forwardly projecting bead 25 may be formed on plate l3 and the rear marginal portions of inner side wall 22 may be arranged to fit over bead 25. Annular combination gaskets and cushioning members 26 of rubber or other compressible elastic material maybe arranged between the filter and plate 23. Openings 2'! may be provided in front and rear walls 23 and these openings may be provided with coarse mesh screen coverings 28. Coverings 28 may be formed by attaching annular sheets of screen to the interior surfaces of front and rear walls 23. Shell 2i may be filled with filtering material 29 which is preferably a mass of fine copper wire having a coating of tacky material, to: example, an oil of such viscosity that a thin film clings to the wire strands. Filtering material 29 also assists the silencer by absorbing sounds which reach it.

A majority of openings 21' communicate with openings M in plate I3. Gaskets 26 serve to prevent the entrance of air around the rear edges of side walls 22 and insure that all air passes through the filtering material. They also prevent relative motion between the two units and any consequent rattling.

Figs. 5 and 6 illustrate a modification of my silencer in which the filtering unit is adapted to be incorporated in the gas passage thereof without resulting in any increase in the size of the silencer. Outer concave shell 3i is similar in all respects to shell i0 except that it is provided with a central opening 32. A ioraminous concave inner shell 33 is attached to outer shell 3| at its periphery. Inner shell 33 has its central portion deformed outwardly into contact with outer shell M. It is also provided with a central opening 35 and has an annular indentation 35 impressed upon it at its intermediate portion. A closed hollow annular shell 36, substantially D-shaped in transverse section, is supported within inner shell in spaced relation thereto. Annular shell carries an annular plate (ii. The inner periphery of plate 31 is secured to a cylinder similar to cylinder I5, and its outer periphery is secured to a U-shaped member 33 similar to annular member to. A bracket 45! is arranged in the air passage, and its ends are secured to the top of U-shaped member 39. Its intermediate portion extends upwardly and its mid-portion abuts the central portion of inner shell 33. The central portion of bracket 40 has opening 4i therein. Bolt 42 threads openings 32, 34, and 4E and when nut 43 is drawn up tightly upon bolt 42 the assembly is fastened rigidly together and annular shell 36 is held in place. Bolt 42 may be spot-welded to bracket 40. The relation of the parts is substantially the same as that of the silencer shown in Fig. 1.

Tongues 45 and 46 project radially outward from the peripheries of member 33 and plate 31, respectively, and are spaced circumferentially desired distances apart. These tongues may be welded together to form the attachment between member 33 and plate 31. The end portions of tongues 46 may be turned rearwardly substantially at right angles to form a plurality of retaining ledges. A cylindrical filtering unit 41 of fine mesh wire may be inserted within the space between member 39 and inner shell 33 with one edge resting against indentation 35 and the other edge resting within tongues 46.

Filtering unit 41 may be of tinned steel wire having an adherent tacky coating of oil as described in connection with filtering material I! shown in Fig. l. Filtering unit 41 is, in this manner, incorporated within and interposed across the air passage of the silencer and no increase in silencer size is made necessary by its presence.

Annular member 36 and the space between concave shells 3i and 33 may be filled with fillings Q8 and 29, respectively, of gaseous pressure-wave absorbing material. The path of the air is substantially the same as that in the silencer illustrated in Fig. 1. Bracket 40 does not obstruct the flow of air to any appreciable extent.

I claim:

1. A silencer comprising a double walled, concave member, the inner wall being foraminous and the space between said walls being filled with soimdebsoz'lomg materiel, o m; a mcmwon having a plurality of spaced openings em clubs shoal (so me Ga s d eoneave attached to the edge of sold concave n". "ceilings adjacent its outer per hollow ioraminous annular member alts/oi sing; 'l'hrough sold plow teem-lg sold plaice disposed interiorly of and "me-1, mellow annular men from said concave member, said annulaa iorateel mezel sulosto having a, central opening registering \1 remsverse section olmeheol central opening in said plate, sold. o cylinder speetlvely onl her being filled with sound-absorbing sold member with y said. inner central openings of said plate W s 25ml specesl annular member respectively, and me member tween said members forming a com 1 ue wave absorb V l passage for said silencer, said spacee l "L l he emee between.

in sale? late registering with said gas e somen cove the imaer wall; "meme performecl sheer, meuol and the so sold filled with 

